1. Field of the Invention
The present invention relates generally to an electronic push-button type door locking device for an automotive vehicle, and more particularly to an electronic door locking system by which vehicle doors can be locked or unlocked when the driver depresses a plurality of push-button type switches in accordance with a predetermined code.
2. Description of the Prior Art
The background of the present invention will be explained with respect to its application to the system used with an automotive vehicle.
As is well-known, there exists an electronic push-button type door locking system for an automotive vehicle, by which vehicle doors can be locked or unlocked when the driver depresses a plurality of push-button type switches installed at an appropriate position on the outside of an automotive vehicle in accordance with a predetermined code. When such an electronic vehicle door locking system as described above is used to lock or unlock the doors, since the vehicle doors can be locked or unlocked by the driver without using the ignition key, it is very convenient for the driver, in particular, when the vehicle is left parked.
In the above-mentioned electronic door locking system, however, since the vehicle doors can be locked from the outside of the vehicle without use of the ignition key, when the driver parks his vehicle, there exists the danger that he might leave his vehicle, after having locked the door by using the electronic push-button type door locking system, with the ignition key left inserted in the ignition keyhole.
In the case where the vehicle is left parked in the driver's own private parking space with the ignition key left in the ignition keyhole, there may be little chance of the vehicle's being stolen; however, in the case where the vehicle is left parked in public out of the driver's sight with the ignition key left in the ignition keyhole, since a thief can readily see whether or not the ignition key is left inserted in the ignition keyhole, there may be a chance that the thief will break the vehicle window to open the vehicle door even if the door is locked by the electronic push-button type door locking system, and may steal the vehicle by using the ignition key left in the keyhole.